I’ve been exploring my new Woodstock Low Power (WLP) HP-25 for about a week and I wanted to share some early impressions with the community.

My configuration is a WLP with IR transmitter and GPS module installed in an HP-25 (non-C model, s/n 1605A…), so I have one with ‘all the bells and whistles’. I used an HP-25 for 3 years in college so I’ve been comfortable with using one in the past and I really like the small form factor, the just-right feeling in the hand, classic HP key-click/feel and of course red LEDs. Although the WLP can be configured as any of the Woodstock models (21, 22, 25, 27, 29, 67) as well as the Classic and Spice series models, most of my testing/playing has been while configured as an HP-25 as this is what the h/w is (keys, labels) and is the model I am most familiar with.

Full Alphabet/Text and Special Character Display: WLP lets you use the complete alphabet (A-Z) plus many common symbols and punctuation, a first for HP LED calculators (probably all LED calculators). Some letters are upper- and some lower-case, and while a few might not be intuitively recognized when viewed by itself, I’ve not found any that are confusing when viewed in the context of the surrounding letters in a word. For example, programs can be saved using fully alphabetic names or descriptions, and as there is sooo much storage space, you will definitely need to use this feature. Entering and editing the letters is simple and quick and having the full alphabet and symbols available enable the next 3 cool features.

Program Mnemonic Display: Program steps can now be stored in mnemonics using the full Alphabet and special characters, so programs now show “SIN” rather than 14 52 (on an HP-25). This is particularly helpful when reviewing a program printout.

IR Printing: You can print to HP’s 82240A and 82240B printers if you add the IR diode transmitter to your WLP. This supports PRINT X, paper advance, TRACE mode, and most of the printing features found on the printing Woodstock machines. I have not experimented much with the print feature yet, but everything I’ve tried has worked just as one would expect. I did not measure IR range, but found it worked to at least 18” from the printer.

Function Name Display: If you hold down a numerical operation key (e.g. COS, X^2, ABS, etc.), the WLP will perform that numerical function, briefly display the result, and then display the mnemonic for that operation. Though not quite as nice as the 41C feature which will let you cancel the operation if you continue to hold it until NULL is displayed, however when you have the WLP configured for a machine different from the actual keyboard (or on an installed overlay) it is very helpful to verify that you pressed the correct key.

Programs Pre-stored: In addition to being able to store 100 of your own programs (each the max size for that model – e.g. 98 steps for a 29C) and 10 sets of register variables for each model calculator, the WLP comes with 55 programs for the HP-25 (54 from the Applications Manual, plus a bonus Battleship game) and the complete HP-67 Standard Pac set of 15 programs already entered and available for use. So even though it's interesting to use the new features to enter programs, these are already in there so you can start exploring fully ready programs right away.

Settings Easily Configured: Settings (for many features I’ve not described at all here) are controlled via a simple screen that lets you check and set the various Flags, including things like date format, show Trig mode, Right-aligned display output, IR enabled, Wakeup keys, etc.

Detailed Manual: Although most key commands are summarized on a nice laminated card which comes with the WLP, the Options, Functions and Modes will need, at least while initially learning them, a bit more explanation and Bernhard provides an excellent PDF manual with thorough but still clear explanation of the feature, how to use it, some advice, etc. Also, the WLP is built upon Panamatik’s earlier Enhanced ACT and many of the WLP’s features are described there. The WLP manual in fact begins by recommending you read that manual first, and it has clear explanations for what is the same as the Enhanced ACT, what is different, and what is completely new in the WLP.

Misc. Functions: Here a few other functions I won't describe in detail, but are worth mentioning: Time, Date, DOW, Storage used, Temperature, Beeper and also a real-time Clock/Calendar and Alarms (which really deserves more explanation here, but this review is already running long).

Really Low Power: As the name implies, the WLP is really, really low power. Anyone that has used a Woodstock for long recognizes that one of its most frustrating limitations is its short battery life. Back in the day, a full charge was good for only 2-3 hours of sustained use. More modern cells can extend that to 4-5 hours, but it still is frustrating and in many cases too limiting to be relied on for a full day of use. With the completely new circuit in Panamatik’s WLP (details explain how in the thread noted at the beginning) this has been dramatically extended such that this is no longer any concern. I have been using my WLP for many (8-10) hours over the past week, and the voltage indicator is still showing the same 2.5V it showed when I started (I’m using 2 new NiCD AA cells). The WLP also powers itself down into sleep mode after 1 minute (configurable) of inactivity so this helps too.

Seamless Integration into Woodstock Personality: I’ve briefly described a few of the WLP’s amazing features here to try to convey what a truly amazing product this is, but in my opinion the true genius of Panamtik’s brilliant product is all these amazing features, modes, capabilities and options are integrated seamlessly into the Woodstock’s simple and intuitive personality in a way that does not in any way interfere with original Woodstock operation. It’s easy to add a new feature to a product, but it’s much harder to add new features that are useful and easily accessed but without interfering with the original UI. Incredibly, the WLP has done this with 20-30 completely new features, extended some existing features, and does this for all 3 families of calculators while preserving the Woodstock’s ease of use and original charm. In fact, if you gave a WLP machine to an experienced Woodstock user, he/she might never even notice that all these great capabilities are in there. Unless they notice it ran faster… or the batteries lasted longer… or that the WLP display says OFF briefly before shutting down.

If you like vintage LED machines, my advice is simple: Get one!

As other WLP users get their machines assembled and running, please add your own comments to this thread about your favorite WLP feature and how you use it.

Thanks a lot for this comprehensive description. I did my best and worked hard for getting this wonderful kind of response.

I still like to get more feedback from other users of my little circuit. More than 15 units are shipped. I got two units back with problems due to external flash memory corruption, only GPS versions showed this problem. I will investigate, how this could happen. Perhaps only the battery needs a buffer capacitor to avoid it. Let's see how I can fix this.

My patient is a 21 wich starts with HP25LP but the key asignemet seems to be wrong. I changed the conector but in my best case, I have the right half of the numeric keys. How can I fix this. Wich wires are to change?

I knew, let your fingers from a good working calculator. It's like a beauty doc, you think you can make a better result. But the way to there could be hard...

Is there a way to make a GPS upgrade without desolder the board? Are there points on the top of the board?

(01-15-2018 08:14 PM)Hans-Peter Wrote: My patient is a 21 wich starts with HP25LP but the key asignemet seems to be wrong. I changed the conector but in my best case, I have the right half of the numeric keys. How can I fix this. Wich wires are to change?

I knew, let your fingers from a good working calculator. It's like a beauty doc, you think you can make a better result. But the way to there could be hard...

Is there a way to make a GPS upgrade without desolder the board? Are there points on the top of the board?

Hans-Peter

Read the LP manual at page 13. If you use an HP-21 board you have to connect pin 1-5 of the "external signals connector" with pin 5-9 of the ACT. Alternatively if you didn't change the LP as you received it, which is for non HP-21 board, just press the "." button before inserting the battery. This is meant for avoiding soldering to rearrange the keyboard wires.

The upgrade can be made from the top of the board, but I don't recommend to solder directly.

(01-15-2018 05:32 PM)PANAMATIK Wrote: I still like to get more feedback from other users of my little circuit.

Very soon :-) Yesterday I got a "defective" HP-22 in the mail. It lies on the operating table right now...

The good thing about the Woodstocks (correct me please if I am wrong!) is that their keyboard/faceplate is interchangeable. So I could implant a Panamatik heart into that broken HP-22 and borrow the keyboard from a working HP-25 without damaging that 25 in every way.

(01-16-2018 11:26 AM)Maximilian Hohmann Wrote: The good thing about the Woodstocks (correct me please if I am wrong!) is that their keyboard/faceplate is interchangeable. So I could implant a Panamatik heart into that broken HP-22 and borrow the keyboard from a working HP-25 without damaging that 25 in every way.

Correct!
Did you check thew 22 is really dead? Luckily I had a really dead 25C that I used to convert into a Woodstock LP.

(01-16-2018 12:26 PM)Harald Wrote: Correct!
Did you check thew 22 is really dead? Luckily I had a really dead 25C that I used to convert into a Woodstock LP.

I nearly got a dead HP-21 for 99 cents the other day. The fellow promised it to me, but gave it to someone else in the end :-(

Would have been a nice home for Bernhards wizardry.

cheers

Tony

Thats a shame you didn't get it. Would have been really cheap
I'll have another look through my parts box. I definately have a shell and probably a PCB. But unfortunately not a keyboard. So if you can find a good keyboard, I could supply the rest...

I spent half of the afternoon with it, cleaning the remains of leaked batteries, checking that the PCB traces are still good, etc. I swapped several parts between this calculator and a working HP-25 but all I get is some "morse code" display of dots and dashes, sometimes also a "0" in every second place of the display. If someone knows if that could be repairable in some way then there is a couple of hours left to save an HP-22 before I will remove the chips and turn it into a Panamatik Low Power.

(01-16-2018 05:05 PM)Maximilian Hohmann Wrote: ... If someone knows if that could be repairable in some way then there is a couple of hours left to save an HP-22 before I will remove the chips and turn it into a Panamatik Low Power.

(01-16-2018 05:25 PM)PANAMATIK Wrote: It could be repaired by the "new ACT" just joking.

OK! So I guess I should be careful when removing the anode and cathode driver ICs because they might still be working? I recently bought a set of "desoldering needles" (across which I stumbled on YouTube) for next to nothing directly from China and will give these a try. They are basically hypodermic needles (the set contains 8 different diameters) with a plastic grip which you are supposed to stick over the IC pins once the solder is molten in order to separate the pins from the PCB.

[/quote]
Read the LP manual at page 13. If you use an HP-21 board you have to connect pin 1-5 of the "external signals connector" with pin 5-9 of the ACT. Alternatively if you didn't change the LP as you received it, which is for non HP-21 board, just press the "." button before inserting the battery. This is meant for avoiding soldering to rearrange the keyboard wires.

The upgrade can be made from the top of the board, but I don't recommend to solder directly.

Bernhard
[/quote]

No luck with your tips. I get the reset but no exepted action by pressing the keys. Is there a way to check the connections between the ACT Pins and the LP Board? Or is it worth to unsolder the LP and see what is wrong? It looks like the rows are swapped from left to right and vice versa. but i have no digits. CHS is on CLX.

I can report a partial success with LP kit number 0008. My donor is an HP-22, Serial Number: 1605S16186.

It took me much more time than expected to desolder the anode and cathode driver chips without causing damage. Initially I tried with my old mechanical desoldering pump but it's opening has grown too large over the years for precise work. Then I tried the desoldering wick provided with the kit but without much success. Next I tried my luck with desoldering needles which I had arrived from China in the meantime. They are very good for removing parts from single sided PCBs and also parts with two or three leads (like that capacitor and the potentiometer under the display) but can't desolder integrated circuits from double sided PCBs.

Desoldering needles are hollow stainless steel needles (basically hypodermic needles) in plastic holders which you push over the component lead with one hand while melting the solder with the other hand. Like this you separate the lead from the PCB contact and it can be pulled out clean. A set with 8 different diameter ones costs less than 2 Euros including shipping from China:

After that I ordered the next cheapest desoldering tool, a mechanical pump with a heated tip. They can be found for example from the well known Belgian electronics retailer Velleman or from various eBay sellers. Mine cost less than 10 Euros including shipping and arrived within two days:

This tools, despite it's ridiculous low cost, works miracles. The two chips were out of the PCB without damage in less than 5 minutes. The best 10-Euro-investment in a long time! Maybe a tool like that should be supplied with every LP or ACT kit (just an idea)?

But now comes the point where I am a bit lost. I cut all traces as required and soldered all pieces into place as described in the manual. At this time I left away all the optionals (IR diode, buzzer, GPS, on-off-switch) for a basic function test. Connecting the board to a laboratory supply set at 2,4V (= 2x NiCd cell) I got instant success :-) The display lights up with it's welcome message, albeit very dim (maybe 2,4V is just a bit low?). But all the keys are off by one column (e.g. pressing "4" produces a "5", some don't seem to do anything at all) and the On-Off switch behaves like "Prgm-Run". So either I made a mistake or the HP-22 board is somehow different?

Before I damage anything I will rather wait for advice!

Regards
Max

NB: Just took another picture of how the 6-pin connector with the red end soldered to ACT pin 4 looks like in an HP-22:

(01-25-2018 12:47 PM)Maximilian Hohmann Wrote: But all the keys are off by one column (e.g. pressing "4" produces a "5", some don't seem to do anything at all) and the On-Off switch behaves like "Prgm-Run". So either I made a mistake or the HP-22 board is somehow different?

Before I damage anything I will rather wait for advice!

Regards
Max

NB: Just took another picture of how the 6-pin connector with the red end soldered to ACT pin 4 looks like in an HP-22:

Looking at the rightmost pin in the picture, it seems to be in contact with the trace that passes the pin it is soldered to. I'd have a closer look at that.

Maybe your calculator is in HP21 mode. See page 14 of the manual for reference.

(01-25-2018 01:13 PM)Harald Wrote: Looking at the rightmost pin in the picture, it seems to be in contact with the trace that passes the pin it is soldered to. I'd have a closer look at that.

I just measured and even re-soldered that pin. That doesn't seem to be the problem!

(01-25-2018 01:13 PM)Harald Wrote: Maybe your calculator is in HP21 mode. See page 14 of the manual for reference.

The welcome screen says "HP-25E LP", but it could of course be that my HP-22 board is wired like an HP-21. I did some more tests and it really looks like the columns are consistently shifted by one, wrapping around. One can actually do calculations, keeping in mind that the "ENTER" key is invoked by pressing "CLX"...

(01-25-2018 02:02 PM)PANAMATIK Wrote: Perhaps I made a mistake and have sent an HP-21 wiring to you.

This it was! Now it works as expected, at least as far as I have tried. Thanks for the help. Now I can go ahead and add IR printing, buzzer and GPS.

And just to confirm: Is it safe to operate the calculator with 3V, e.g. by using two normal alkaline batteries? Not that I want to waste batteries, but at my current 2,4V the display is quite difficult to read in daylight.

(01-25-2018 03:05 PM)Maximilian Hohmann Wrote: This it was! Now it works as expected ...

And just to confirm: Is it safe to operate the calculator with 3V, e.g. by using two normal alkaline batteries? Not that I want to waste batteries, but at my current 2,4V the display is quite difficult to read in daylight.

Regards
Max

Congratulations !!! I hope you accept my apologies for the wrong HP-21 wiring, which I made. My prototypes both were HP-21 boards. After testing all LP boards on my HP-21, I had to resolder the 6-pin connector before shipping, and obviously I forgot it in your case.

The LP can be driven with 3.3V (up to 4 V maximum rating according to datasheet, but I never tried that). No problem with alkalines. I think the display will also be bright enough at 2.8V with NiMh.